Abstract
This paper describes experimental results concerning with the effects of DC excitation of transformer core caused by geomagnetically-induced currents (GIC).
As a first step, we investigated the response to DC excitation using three different small scale core models.
The results demonstrated that a single phase three-legged core form is most susceptible to DC excitation, and that a three phase three-legged core form is not affected by DC currents.
We also fabricated large scale single phase shell and core form transformers to evaluate local heating effect caused by DC excitation, since this single phase core form is most susceptible to DC excitation. The results of these experiments showed that transformer heating levels caused by DC currents can be quantitatively estimated.
